Sometimes a trial of a free app ends there. The app just isn't compelling enough to even continue to play with the free version. Or, the free version is good enough to keep, but not quite enough to tip you over to purchase. But others, either by offering additional capabilities or content, have been worthy of paying for the full version. Which iPad or iPhone apps have you upgraded? And why?
Only two I can think of Space Miner Blast and Voiceplus Voice Changer. Truthfully though I have barely touched either of them since, I guess I bought blast because I liked space ore bust and voiceplus well it does change voices pretty well which is what it promised although I probably should have just went with another one. It's doubtful I'll do it again I just don't like IAP of any sort (although I am looking forward to the GOF 2 one).
Ill second space miner blast, and judging by the achievement I got for playing at least 10 hrs, i think i got my 1.99 worth of gameplay
Zero for games, only three for other apps, Atomic Web Browser, Autodesk Sketchbook, and Soundhound. I don't think I will upgrade free games anytime soon though, there are too many paid games I haven't even finished/bored yet.